What is Real Ear Measurement?

When you’re fit with hearing aids, one of the many ways your hearing provider may ensure your hearing aids perform properly is by conducting a test called Real Ear Measurement (REM). REM is one of the most valuable tools hearing providers have at their disposal. It allows for a more precise, personalized fitting, based on the exact acoustic signature of your ears. In this post we’ll examine what REM is, the benefits of REM, and why you may or may not have REM performed when being fit with hearing aids.

What is Real Ear Measurement?

Real Ear Measurement is a short test (5-20 minutes) conducted by your hearing provider, which ensures that your hearing aids are providing the right amount of sound to your eardrum. Once your newly fitted hearing aid is programmed and in your ear, your provider will insert a tiny probe device in your ear canal, which sits very close to the eardrum. This probe measures the sound at your eardrum and ensures the hearing aid is applying the appropriate gain at each frequency.

What benefits does REM provide?

In short the benefit of REM is that it allows for more fine-tuned, accurately fitted hearing aids.

To explain the benefits of REM, let me first introduce a hypothetical scenario. Imagine that you just got your hearing tested, and you find out that hear perfectly at every frequency except 2000 Hz. The goal of hearing aids then, would be to amplify sounds for you at 2000 Hz, so you have your normal range of hearing back. So your hearing provider programs your new hearing aids and puts them in your ears. Let’s assume that the the hearing aid is programmed perfectly according to the manufacturer’s fitting software, and it’s outputting, for example, 20 db of gain at 2000 Hz, but for some reason your hearing aids just don’t sound right.

So the hearing aid is programmed perfectly, it’s outputting the correct gain according to the fitting algorithm, but why doesn’t it sound right? The answer lies in the fact that every single ear canal has a different shape, diameter, resonance, and length. When the hearing aid outputs a certain amount of sound, that doesn’t necessarily mean that that’s the amount of sound that reaches the eardrum. For instance, if you have a sharp bend in your ear canal, it could drastically dampen the sound before it reaches your eardrum. Now, the fitting software might show your hearing provider that the hearing aid is outputting the appropriate amount of gain, but it can’t show how much actual gain is reaching your eardrum at each frequency.

To explain it in another way, consider speaking into 2 different sized tubes of wrapping paper. The sound output (from your mouth), is exactly the same when you speak into both sized tubes, but due to the varying length, diameter, and thickness of the wrapping paper tube, the end sound could vary greatly. The same thing can happen with hearing aids. Hearing providers can program hearing aids to output a certain amount of volume, but the actual volume reaching the eardrum could be quite different.

It is the job of REM to ensure that the actual amount of sound that reaches your eardrum is the correct amount needed based on your prescription. Once REM has been completed, your hearing provider will be able to see how much actual gain is being applied at each frequency vs. how much gain the fitting algorithm says should be applied. With these results, your hearing provider can then tweak the gain at various frequencies to ensure that you are getting the appropriate amount of volume at each frequency.

How important is Real Ear Measurement?

Real ear measurement has been around for at least 25 years, but it is still not a widely used test. According to this article, only around 30% of hearing providers routinely conduct REM. If I had to guess, I would say that figure is actually high, and that more like 20% of providers do REM, and maybe less. If you look at those figures, you might conclude that REM must not be that important, but it is widely accepted in the audiology community that REM is a best practice, and a gold standard of care.

So why aren’t more providers doing REM?

The equipment is expensive, and sometimes hard to learn: The equipment needed to conduct REM can easily run upwards of $10,000. For this reason, it’s quite a financial burden for many young practices, and an investment that they simply can’t afford. At the same time, with some equipment, there is quite a learning curve that some providers simply aren’t willing to deal with.

REM takes time to conduct- time that some providers don’t have: Many hearing providers are very busy people. When I was dispensing, I had many days where I saw 25 patients, and time was certainly limited. For this reason, a lot of providers keep REM in their “back pocket” as a tool that can be used, but simply don’t have the time to do it for every patient.

Some providers aren’t convinced of the benefit of REM: This is the main reason why a lot of providers don’t do REM. Here’s the thing- REM tells you how you should adjust a hearing aid, but it doesn’t take into account that patient’s perceptions. For example, if the results of REM indicate that more volume should be applied at a certain frequency, but then a patient doesn’t like that adjustment, the provider is obviously not going to follow the recommendations of the REM. Often, providers get the best results for their patients simply by asking “how does that sound?”- and that’s really the case for almost all fittings. For this reason, a lot of providers never conduct REM, or only reserve it for those difficult fitting as a last resort.

Are any of the above valid reasons to not conduct Real Ear Measurement? Maybe, with exceptions.

Here’s my bottom-line opinion:
As you search for a hearing provider, I wouldn’t go so far as to say REM absolutely needs to be something they offer, but they should offer some type of fitting verification. A few manufacturers today even include verification tools in their fitting software, Starkey’s SpeechMapping feature is a good example. So as long as some kind of fitting verification is taking place, I think that will suffice for the majority of hearing aid fittings, and leave patients very satisfied- which is the most important thing of all.

Now, if you’ve gone back and forth with your hearing provider, made several adjustments, and REM is not something they have available to offer you, then I think at that point it’s worth it to seek out a provider that does routinely do REM, as there is a very good probability it will make the difference for your fitting.